1. Field of the Invention:
The present invention relates to a semiconductor device of the Quad Flat Non-leaded (QFN) package type, and a method of making the same.
2. Description of the Related Art:
FIG. 6 is a plan view showing a prior art semiconductor device S3 of the Quad Flat Non-leaded (QFN) package type. FIG. 7 is a sectional view taken along lines VII—VII of FIG. 6. The semiconductor device S3 includes a semiconductor chip 31, a die-pad 32 on which the semiconductor chip 31 is mounted, a plurality of leads 33, and a sealing resin 34 which is illustrated as transparent in FIG. 6. The semiconductor chip 31 is electrically connected to the die-pad 32 via a first wire 41 for grounding. Each of the leads 33 is electrically connected to the semiconductor chip 31 via a second wire 42. The sealing resin 34 seals the semiconductor chip 31, the first wire 41 and the second wires 42 while exposing the lower surface 32b of the die-pad 32 and part of each lead 33.
In the semiconductor device S3, the lower surface 32b of the die-pad 32 is exposed to the outside. Therefore, as indicated by the arrow A in FIG. 8, water is likely to enter through the boundary between the die-pad 32 and the sealing resin 34 and may reach the upper surface 32a of the die-pad 32. In the reflowing process for mounting the semiconductor device S3 onto a mother board (not shown), when the die-pad 32 is heated while containing water on the upper surface 32a, the sealing resin 34 is removed from the die-pad 32 to shrink in the arrow B direction. As a result, the sealing resin 34 exerts a stress to the first wire 41, which may lead to the breakage of the first wire 41.